Process for the production of acylisocyanide dichlorides and carboxylic acid chlorides

ABSTRACT

Acylisocyanide dichlorides and carboxylic acid chlorides are obtained by reacting a carboxylic acid anhydride and an isocyanide dichloride in the presence of a Lewis acid at a temperature of from 0* to 300* C.

United States Patent 1 Findeisen et al.

1 Sept. 11, 1973 PROCESS FOR THE PRODUCTION OF ACYLISOCYANIDEDICHLORIDES AND CARBOXYLIC ACID CHLORIDES Inventors: Kurt Findeisen;Kuno Wagner, both of Leverkusen, Germany Assignee: BayerAktiengesellschaft,

Leverkusen, Germany Filed: July 19, 1971 Appl. No.: 164,038

Foreign Application Priority Data July 21, i970 Germany P 20 36171.]

US. Cl. 260/544 C, 260/290 P, 260/326.8, 260/453 P, 260/544 M, 260/544L, 260/544 Int. Cl. C07c 51/58 Field of Search 260/544 C, 453 P Kuhle etal. Angew Chem. Int. Edit. VOL 4, (1965) No. l l

Primary Examiner-Lorraine A. Weinberger 5M"? "':."?:B Di Attorney-RalphD. Dinklag e and Arnold Sprung [57] ABSTRACT Acylisocyanide dichloridesand carboxylic acid chlorides are obtained by reacting a carboxylic acidanhydride and an isocyanide dichloride in the presence of a Lewis acidat a temperature of from 0 to 300 C.

9 Claims, No Drawings PROCESS FOR THE PRODUCTION OF ACYLISOCYANIDEDICIILORIDES AND CARBOXYLIC ACID CHLORIDES BACKGROUND This inventionrealtes to a process for the production of acylisocyanide dichloridesand carboxylic acid chlorides.

Although it is known that isocyanide dichlorides can be reacted withinorganic acid anhydrides, e.g., P only poor yields of isocyanates areobtained under the usual reaction conditions because of secondaryreactions (Angew. Chemie, 81, (1969) page l9).

SUMMARY It has now surprisingly been found that high yields ofacylisocyanide dichlorides and carboxylic acid chlorides can be obtainedin a smooth reaction by reacting a carboxylic acid anhydride with anisocyanide dichloride corresponding to the formula in which R representshalogen, a lower alkyl radical, a lower alkyl radical substituted byhalogen atoms, an aryl radical optionally substituted by halogen, loweralkyl, lower alkoxy or nitro or a nitrogen-containing heterocyclicradical comprising a 5- or 6-membered ring optionally substituted byhalogen atoms, in the presence of a Lewis acid at a temperature in therange from 0 to 300 C.

DESCRIPTION Apart from bromine and fluorine, preferred halogen atoms forinclude chlorine. Lower alkyl and alkoxy radicals contain one to fourand preferably one or two carbon atoms and may optionally be substitutedby the aforementioned halogen atoms. In addition to the naphthyl.radical, the phenyl radical is a preferred optionally substituted arylradical. Substituents on the aryl radical include the aforementionedhalogen atoms and also the aforementioned lower alkyl and alkoxy groups.The nitrogen-containing heterocyclic ring system can contain up to threenitrogen atoms and may optionally be anellated with a benzene ringsystem.

The reaction is carried out at a temperature of from 0 to 300 C.,preferably at a temperature of from 50 to 200 C., most preferably at atemperature of from l00 to 160 C.

The isocyanide dichlorides used in the process according to theinvention are known and can be obtained by known methods. The majorityof the isocyanide dichlorides suitable for use in the process aredescribed in Angew. Chemie 79, pages 663-680 (1967) and in Angew. Chemie80, pages 942-953 (1968), both of which are incorporated herein byreference.

lsocyanide dichlorides preferably used in the process includedichloromethyl isocyanide dichloride; trichlo-' romethyl isocyanidedichloride; l,l-dichloro-2- chloroethyl isocyanide dichloride;pentachloroethyl isocyanide dichloride; and l-phenyl-l l ,3 ,3-tetrachloro-2-aza-propene.

The majority of carboxylic acid anhydrides suitable for use in theprocess are described in Houben-Weyl, Vol. VIII (1952), pages 476-801,and in G.A. Olah Friedel-Crafts and related reactions" Vol. III, pages550-598 (1964), both of which are incorporated herein by reference.

0f the carboxylic acid anhydrides quoted in the aforementionedliterature references, it is of course possible to use any of thosewhich do not contain any functional groups that would be capable ofreacting with isocyanide dichlorides. The majority of these compoundscorrespond to the general formula in which the radicals R, which can bethe same or different represent substituted or unsubstituted aliphatic,cycloaliphatic, aromatic or heterocyclic radicals, or together representa group of the formula -CH=CI-lor -(CH,),,- (wherein n represents aninteger from 1 to 4), or a group of the formula the remaining valencebonds of which are satisfied by inert substituents or form part of aheterocyclic, cycloaliphatic, hydroaromatic or carbocyclic-aromatic ringsystem.

Naturally, aliphatic radicals also include cycloaliphatic rings.Cycloaliphatic rings are those with five to twelve, preferably with fiveor six, carbon atoms in the ring system.

Aromatic radicals are those with up to 20 carbon atoms in the ringsystem, preferably with up to 14 carbon atoms, most preferably with l2,10 or six carbon atoms.

Heterocyclic radicals are those with 5, 6 and 7 membered rings,preferably with 6 membered rings, which contain as hetero atoms oxygen,nitrogen or sulphur, preferably nitrogen and, in the case of 5- memberedrings, oxygen or sulphur in addition to nitrogen.

The following are examples of substituents for the radicals R or for thering systems in which they are present together Halogens (preferablyfluorine, chlorine or bromine); The cyano; nitro, COCl-; SO,Cl-;trifluoromethyl; alkoxy groups, preferably with one to four carbonatoms; alkylcarboxy groups (preferably with one to six carbon atoms);benzyl; phenethyl; aroyl (especially benzoyl or naphthoyl); alkoxy,preferably with one to four carbon atoms; aryloxy (especially phenoxy ornaphthoxy); aryl (preferably phenyl or naphthyl); and, especially in thecase of the carbocyclic heterocyclic ring systems, especially those ofaromatic character, alkyl radicals with one to eight, preferably withone to four, carbon atoms. Particular reference is made to the factthat, contrary to the exception made in the quotation of carboxylic acidanhydrides, the carboxylic acid and sulphonic acid groups alsoconstitute such substituents, even in the form of single or mixedanhydrides. COCl is formed from COOH, whilst mixed acid chlorides areformed from mixed anhydrides, for example in accordance with thefollowing equation:

The following are examples of suitable anhyd fig] acetic anhydride,propionic acid anhydride, butyric acid anhydride, succinic acidanhydride, glutaric acid anhydride, maleic acid anhydride,hexahydrophthalic acid anhydride, 4-methyl hexahydrophthalic acidanhydride, tetrahydrophthalic acid anhydride, phthalic acid anhydride,tetrachlorophthalic acid anhydride, tetrabromophthalic acid anhydride,naphthalic acid anhydride, 4-nitronaphthalic acid anhydride,pyromellitic acid dianhydride, perylene tetracarboxylic acid-3,4;9,10-dianhydride, benzophenone-3,4;3',4'- dianhydride, or bcnzoicacid sulphonic acid-(2)-endoanhydride.

The Lewis acids used for the process according to the invention are alsoknown (G.A. Olah Friedel-Crafts and Related Reactions Vol. 1, pages 2530, J. Wiley & Sons, 1963), which is incorporated herein by reference.

Examples of suitable Lewis acids include ferrous chloride, stannicchloride, antimony trichloride, antimony pentachloride, borontrifluoride, boron trifluoride etherate, stannous chloride, hydrogenchloride, a luminium chloride hydrochloride (HAlCl and preferably ferricchloride and zinc chloride.

The process is carried out simply by combining the reaction components.In general, the molar ratio is about 1:1. The catalyst is generally usedin a quantity of from 0.1 to percent by weight, preferably in a quantityof from 1 to 3 percent by weight, based on the isocyanide dichloride. Itis of course also possible, when desired, to use larger quantities ofcatalyst. The fact that the process according to the invention can becarried out at all must be regarded as particularly surprising, becausesecondary reactions had been expected according to the literature.However, acyl isocyanide dichlorides and dicarboxylic acid chlorides aresurprisingly obtained in high yields in the absence of secondaryreactions by the process according to the invention. Even the otherwisesubstantially inaccessible fumaric acid dichloride can be obtained inhigh yields and in highly pure form. The process is illustrated by wayof example below with reference to the reaction of trichloromethylisocyanide dichloride with maleic acid anhydride, chlorocarbonylisocyanide dichloride and fumaric acid dichloride being obtained:

trans The process according to the invention is generally carried out inthe absence of solvents. If the melting point of one of the reactants isabove the reaction temperature, or if one reactant is insoluble in theother, it is best to use inert solvents such as chlorobenzene,dichlorobenzene, nitrobenzene or dioxan etc., in order to accelerate thereaction.

If the reaction temperature is above the boiling point of one of thereagents, the reaction can be carried out in a suitable pressure vessel.The process can of course be carried out either continuously orbatchwise. The oxygen-containing compounds formed during the reactionfrom the isocyanide dichlorides are usually in the form of the acylisocyanide dichlorides. it is, however, known from the literature(Angew. Chemie 74, 848-855 (1962) that chlorotropy can occur in acylisocyanide dichlorides. In the present instance, too, the effect of thiswould be that the corresponding isocyanates and the correspondingchlorocarbonyl imide chlorides would be formed instead of acylisocyanide dichlorides.

The reaction mixtures can be worked up in the usual way by distillation.The compounds which can be obtained by the process according to theinvention, some of which are extremely difficult to obtain otherwise,are valuable intermediates for the production of pesticides, dyes andplastics, and are themselves active in these directions.

The general usefulness of the carboxylic acid or dicarboxylic acidchlorides obtainableby the process according to the invention is known.For example, phthaloyl chloride can beconverted into a yellow dye with1- amino anthraquinone in accordance with U. S. Pat. specification No.2,727,044. Phthaloyl chloride can of course also be used in thesynthesis of plasticisers, synthetic resins and the like and for theproduction of organic compounds (cf. Chemielexikon: H. Rompp, Vol. 3,page 4921, 6th edition). Acetyl chloride is known as a reagent inchemical analysis and is used as a catalyst for esterificationreactions, for the halogenation of aliphatic acids and for chemicalsynthesis, for example in the production of acetyl salicyclic acid(Chemielexikon: Rompp,l, p. 31, 6th, ed.). Longer-chain dicarboxylicacid chloride can be used in the production of polyamides; see U. S.Pat. No. 2,130,523; and Journal Polym. Science 40, page 289 (1959). Theacyl isocyanide dichlorides formed during the reaction can also be usedin known manner for further reactions. For example, they are suitablefor the production of stabilisers for plastics. Because of theirsensitivity to moisture and water, they can also be used as dehydratingagents. They are also suitable for use as intermediates in theproduction of fungicides, for example by reaction with o-phenylenediamine (see Belgian Pat. No. 752,513, and German Offenlegungsschrift P,19 32 297.5).

The following examples, wherein the temperatures are given in C, areintended to further illustrate this invention without limiting same.

EXAMPLE 1 49.6 g of phthalic acid anhydride, 71.6 g of trichloromethylisocyanide dichloride and 1 g of ferric chloride are heated for 4 hoursat C. in a spherical flask. The following are obtained duringdistillation 66 g of phthalyl chloride (92.5 percent of the theoretical)b. p. 13lC./9 Torr and 52 g of chlorocarbonyl isocyanide dichloride (92percent of the theoretical) b.p. 123 125C./76 0 Torr.

EXAMPLE 2 149.25 g of pentachloroethyl isocyanide dichloride and 74 g ofphthalic acid anhydride are mixed while stirring with 2 g of ferricchloride in a 250 ml capacity 3-necked flask. The mixture is then heatedwith stirring for 5 hours at 165 C. The reaction mixture is distilled,giving 104 g of pentachloroethyl isocyanate (82 percent of thetheoretical). b.p. 89 93C./12 Torr, and 98 g of phthalyl chloride (96.5percent of the theoretical), b.p. 133C./10 Torr.

EXAMPLE 3 77 g of hexahydrophthalic acid anhydride and 107.5 g oftrichloromethyl isocyanide dichloride are heated for 3 hours at 140 C.in the presence of 2 g of aluminium chloride in a 0.3 litre capacityautoclave. After the autoclave has been flushed with nitrogen andemptied, its contents are distilled, giving 75 g of hexahydrophthalicacid dichloride (72.5 percent of the theoretical) b.p. 120 126C./15Torr, and 69 g of chlorocarbonyl isocyanide dichloride (86 percent ofthe theoretical) of b.p. 125 C.

EXAMPLE 4 375 g of maleic acid anhydride are introduced into a 1.5 litrecapacity 3-necked flask, followed by the addition through a droppingfunnel of 821 g of trichloromethyl isocyanide dichloride. Following theaddition of 8 g of stannic chloride, the mixture is heated for 60minutes at 130 C., as a result of which the reaction mixture begins toboil under reflux. The reaction is over after 3 hours at thistemperature. The reaction products obtained are fractionated, giving 543g of fumaric acid dichloride (93 percent of the theoretical), b.p. 158160 C., and 540 g of chlorocarbonyl isocyanide dichloride (88 percent ofthe theoretical), b.p. 123 125 C.

EXAMPLE 5 100 g of 1-phenyl-1,1,3,3tetrachloro azapropene are heatedwith stirring for 3 hours at 140 C. with 38.1 g of maleic acid anhydrideand a small quantity (taken from the tip of a spatula) of zinc chloride.On completion of the reaction, the reaction mixture is fractionatedgiving 46 g of fumaric acid dichloride (75 percent of the theoretical),b.p. 158 160C./760 Torr, and 52 g of 'a-chlorobenzylidene carbamic acidchloride (66 percent of the theoretical), b.p. 145 150C./l2 Torr.

EXAMPLE 6 75 g of acetic acid anhydride and 158 g of trichloromethylisocyanide dichloride are gradually heated to 100 C. in the presence ofl g of ferric chloride. Refluxing in the condenser is noticeable attemperatures as low as 97 C. The reaction mixture obtained is distilled,giving 108 g of acetyl chloride (94 percent of the theoretical) and 66 gof chlorocarbonyl isocyanide dichloride (78 percent of the theoretical).

EXAMPLE 7 65 g of propionic acid anhydride and 107.5 g oftrichloro-methyl isocyanide dichloride are heated for 3 hours at 60 C.with 2 g of stannous chloride. Distillation gives 67 g of propionic acidchloride (71.5 percent of the theoretical) and 49 g of chlorocarbonylisocyanide dichloride (61.5 percent of the theoretical).

EXAMPLE 8 92 g of benzoic acid-sulphonic acid endoanhydride, 107.5 g oftrichloromethyl isocyanide dichloride and 2 g of ferrous chloride areheated for 2 hours at C. in 300 m1 of o-dichlorobenzene. On completionof the reaction, the chlorocarbonyl isocyanide dichloride and theo-dichlorobenzene are separated by distillation, and the residueobtained is recrystallised from petroleum ether, giving 65 g ofchlorocarbonyl isocyanide dichloride (81 percent of the theoretical) and86 g of benzoyl chloride-2-sulphochloride (72 percent of thetheoretical) of b.p. 37 39 C.

EXAMPLE 9 72.7 g of benzene tetracarboxylic acid anhydride and 143.6 gof trichloromethyl isocyanide dichloride are heated for 1 hour at 50 C.and for 1 hour at 140 C. in the presence of 2 g of ferric chloride. Theresulting reaction mixture is distilled, giving 99 g of benzene-1,2,4,5-tetracarboxylic acid chloride (91 percent of the theoretical),b.p. 174 176 C./2 Torr, and 98.5 g of chlorocarbonyl isocyanidedichloride (92 percent of the theoretical).

EXAMPLE 10 57 g of glutaric acid anhydride and 107.5 g oftrichloromethyl isocyanide dichloride are heated for 10 minutes at 140C. in the presence of zinc chloride. The dark-coloured reaction solutionis distilled, giving 52.5 g of glutaric acid dichloride (62 percent ofthe theoretical), b.p. 107 l08C./16 Torr, and 63.5 g of chlorocarbonylisocyanide dichloride (79 percent of the theoretical).

What we claim is:

1. Process for preparing chlorocarbonyl isocyanide dichloride andcarboxylic acid chlorides which cornprises reacting a carboxylic acidanhydride having the formula CII-CH or the remaining valence bonds ofwhich are satisfied by inert substitutents or form part of aheterocyclic, cycloaliphatic, hydroaromatic or carbocyclic-aromatic ringsystem, with trichloromethyl isocyanide dichloride in the presence of aLewis acid at a temperature of from 0 to 300C.

2. Process as claimed in claim I, wherein the Lewis acid is selectedfrom the group of aluminium chloride, ferrous chloride, ferric chloride,zinc chloride, stannous chloride, stannic chloride, antimonytrichloride, antimony pentachloride, boron trifluoride, borontrifluoride etherate, hydrogen chloride and aluminium chloridehydrochloride.

3. Process as claimed in claim 1 wherein the temperature is from 50 to200 C.

4. Process as claimed in claim 1 wherein the temperature is from 100 to160 C.

5. Process as claimed in claim 1 wherein the carboxylic acid anhydrideis selected from the group of aceticanhydride, propionic acid anhydride,butyric acid anhydride, succinic acid anhydride, glutaric acidanhydride, maleic acid anhydride, hexahydrophthalic acid anhydride,4-methyl hexahydrophthalic acid anhydride, tetrahydro-phthalic acidanhydride, phthalic acid anhydride, tetrachlorophthalic acid anhydride,tetrabromophthalic acid anhydride, naphthalic acid an- 8 hydride,4-nitronaphthalic acid anhydride, pyromcllilic acid dianhydride,perylene tetracarboxylic acid- 3,4;9,l0-dianhydride,benzophenone-3,4;3',4'- dianhydride and benzoic acid sulphonicacid-(2)-endo anhydride.

6. Process as claimed in claim 1 wherein the amount of Lewis acid isfrom 0.1 to l0 percent by weight, based on trichloromethyl isocyanidedichloride.

7. Process as claimed in claim I wherein the amount of Lewis acid isfrom 1 to 3 percent by weight, based on trichloromethyl isocyanidedichloride.

8. Process as claimed in claim 1 wherein one of the reactants has amelting point above the reaction temperature or is insoluble in theother reactant and wherein reaction is carried out in an inert solvent.

9. Process as claimed in claim 8 wherein the solvent is chlorobenzene,dichlorobenzene, nitrobenzene or dioxan.

t III i t

2. Process as claimed in claim 1, wherein the Lewis acid is selectedfrom the group of aluminium chloride, ferrous chloride, ferric chloride,zinc chloride, stannous chloride, stannic chloride, antimonytrichloride, antimony pentachloride, boron trifluoride, borontrifluoride etherate, hydrogen chloride and aluminium chloridehydrochloride.
 3. Process as claimed in claim 1 wherein the temperatureis from 50* to 200* C.
 4. Process as claimed in claim 1 wherein thetemperature is from 100* to 160* C.
 5. Process as claimed in claim 1wherein the carboxylic acid anhydride is selected from the group ofaceticanhydride, propionic acid anhydride, butyric acid anhydride,succinic acid anhydride, glutaric acid anhydride, maleic acid anhydride,hexahydrophthalic acid anhydride, 4-methyl hexahydrophthalic acidanhydride, tetrahydro-phthalic acid anhydride, phthalic acid Anhydride,tetrachlorophthalic acid anhydride, tetrabromophthalic acid anhydride,naphthalic acid anhydride, 4-nitronaphthalic acid anhydride,pyromellitic acid dianhydride, perylene tetracarboxylicacid-3,4;9,10-dianhydride, benzophenone-3,4;3'', 4''-dianhydride andbenzoic acid sulphonic acid-(2)-endo anhydride.
 6. Process as claimed inclaim 1 wherein the amount of Lewis acid is from 0.1 to 10 percent byweight, based on trichloromethyl isocyanide dichloride.
 7. Process asclaimed in claim 1 wherein the amount of Lewis acid is from 1 to 3percent by weight, based on trichloromethyl isocyanide dichloride. 8.Process as claimed in claim 1 wherein one of the reactants has a meltingpoint above the reaction temperature or is insoluble in the otherreactant and wherein reaction is carried out in an inert solvent. 9.Process as claimed in claim 8 wherein the solvent is chlorobenzene,dichlorobenzene, nitrobenzene or dioxan.